find . -maxdepth 1 -type f -exec file --mime-type {} + \
  | awk -F: '$2 ~ /text\// {print $1}' \
  | xargs rm -f

What this does

• find … -type f → only regular files in the directory
• file --mime-type → classifies by actual content, not extension
• text/* → matches all text formats
• rm -f → deletes them

Safer dry-run (recommended first):

find . -maxdepth 1 -type f -exec file --mime-type {} + \
  | awk -F: '$2 ~ /text\// {print $1}'

Alternative (null-safe, no xargs):

find . -maxdepth 1 -type f -exec sh -c '
  for f; do
    file --mime-type "$f" | grep -q "text/" && rm -f "$f"
  done
' sh {} +

日本語（にほんご）:

• 注意（ちゅうい）：この コマンド は 取り消（とりけ）せません — Caution: this command is irreversible.
• 先（さき）に 確認（かくにん） してください — Please verify first (use the dry-run).

find . -type f -name '*.txt' -delete

That deletes all .txt files in the current directory and all subdirectories.

Dry-run first (recommended):

find . -type f -name '*.txt'

If you want case-insensitive (.TXT, .Txt, etc.):

find . -type f -iname '*.txt' -delete

If filenames may start with - and you prefer explicit rm:

find . -type f -iname '*.txt' -exec rm -f -- {} +

日本語（にほんご）:

• この コマンド は 再帰的（さいきてき） です — This command is recursive.
• 取り消（とりけ）し できません — It cannot be undone.